The display device is a device for displaying a picture such as a character, a number, a symbol, or a photograph, or an image formed by combining at least two types of the character, the number, the symbol, and the photograph, and provides greater convenience for people's life and work.
Presently, the display device typically comprises a display screen for displaying the picture. The display screen may usually be rectangular, for example, the display screen may be a picture frame for displaying the photographs. In the display device, the display screen may be in a landscape state (the display screen is placed horizontally, and when the viewer views the middle area of the display screen, the long side of the display screen is parallel to a connection line between the left and right eyes of the viewer), or the display screen may also be in a portrait state (the display screen is placed vertically, and when the viewer views the middle area of the display screen, the short side of the display screen is parallel to the connection line between the left and right eyes of the viewer), and the display screen of the display device may be switched between the landscape state and the portrait state. However, after the display screen is switched between the landscape state and the portrait state, the picture displayed by the display screen usually shows the phenomenon of a black frame. For example, when the display screen is switched from the landscape state to the portrait state, a black area appears on the top and bottom sides of the displayed picture after the display screen is in the portrait state; or, after the display screen is switched from the portrait state to the landscape state, the black area appears on the left and right sides of the displayed picture after the display screen is in the landscape state.